OJ-Problems-Source/HDOJ/3760_autoAC.cpp

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#include <iostream>
using namespace std;
const int maxn = 100005;
const int maxm = 400005;
const int inf = 1000000005;
int head[maxn], vert[maxm], colo[maxm], noxt[maxm], cunt;
int sdis[maxn], edis[maxn], path[maxn], leng;
int queue[maxn], qhead, qtail;
bool vis[maxn], rit[maxn];
void init(int n)
{
cunt = 0;
for (int i = 0; i <= n; i++)
{
head[i] = -1;
sdis[i] = -1;
edis[i] = -1;
vis[i] = 0;
rit[i] = 0;
path[i] = inf;
}
}
void addedge(int x, int y, int c)
{
vert[cunt] = y;
colo[cunt] = c;
noxt[cunt] = head[x];
head[x] = cunt++;
}
void BFS(int start, int *dis)
{
dis[start] = 0;
qhead = qtail = 0;
queue[qtail++] = start;
while (qhead < qtail)
{
int x = queue[qhead++];
for (int p = head[x]; p != -1; p = noxt[p])
{
int y = vert[p];
if (-1 == dis[y])
{
dis[y] = dis[x] + 1;
queue[qtail++] = y;
}
}
}
}
void IdeadPath()
{
qhead = qtail = 0;
queue[qtail++] = 1;
int step = 0;
while (qhead < qtail)
{
int ttail = qtail;
while (qhead < ttail)
{
int x = queue[qhead++];
for (int p = head[x]; p != -1; p = noxt[p])
{
int y = vert[p];
int c = colo[p];
if (rit[y] && sdis[y] == step + 1)
{
if (c < path[step])
{
path[step] = c;
for (int i = ttail; i < qtail; i++)
vis[queue[i]] = 0;
qtail = ttail;
vis[y] = 1;
queue[qtail++] = y;
}
else if (c == path[step] && !vis[y])
{
vis[y] = 1;
queue[qtail++] = y;
}
}
}
}
step++;
}
}
int main()
{
int test, cas;
int n, m, a, b, c;
scanf("%d", &test);
for (cas = 1; cas <= test; cas++)
{
scanf("%d %d", &n, &m);
init(n);
for (int i = 0; i < m; i++)
{
scanf("%d %d %d", &a, &b, &c);
if (a == b) continue;
addedge(a, b, c);
addedge(b, a, c);
}
BFS(1, sdis);
BFS(n, edis);
leng = sdis[n];
for (int i = 1; i <= n; i++)
{
if (sdis[i] + edis[i] == leng)
rit[i] = 1;
}
IdeadPath();
printf("%d\n", leng);
for (int i = 0; i < leng; i++)
{
if (i) printf(" ");
printf("%d", path[i]);
}
printf("\n");
}
return 0;
}